Support None

pyaskit/types/__init__.py

@@ -11,6 +11,7 @@
     code,
     record,
     ref,
+    none,
     IntType,
     FloatType,
     StringType,
@@ -22,5 +23,6 @@
     UnionType,
     CodeType,
     RecordType,
+    NoneType,
     Type,
 )

pyaskit/types/converter.py

@@ -27,4 +27,6 @@ def convert_type(x):
     #     return t.literal(*get_args(x))
     elif origin is dict:
         return t.record(convert_type(args[0]), convert_type(args[1]))
+    elif origin is None:
+        return t.none
     return x

pyaskit/types/schema.py

@@ -52,6 +52,9 @@ def visit_ref(self, type: t.RefType):
             self.type_defs[type.name] = None
             self.type_defs[type.name] = type.access().accept(self)
         return type.name
+
+    def visit_none(self, type):
+        return "null"
 
 
 # export function generateSchema<T>(type: any): string {

pyaskit/types/type_printer.py

@@ -60,3 +60,6 @@ def visit_record(self, type):
 
     def visit_ref(self, type):
         return type.name
+
+    def visit_none(self, type):
+        return "None"

pyaskit/types/types.py

@@ -38,6 +38,9 @@ def visit_record(self, type):
 
     def visit_ref(self, type):
         raise NotImplementedError("visit_ref method not implemented")
+
+    def visit_none(self, type):
+        raise NotImplementedError("visit_none method not implemented")
 
 
 class Type:
@@ -52,6 +55,17 @@ def accept(self, visitor):
         raise NotImplementedError("accept method not implemented")
 
 
+class NoneType(Type):
+    def validate(self, value):
+        return value is None
+
+    def accept(self, visitor):
+        return visitor.visit_none(self)
+
+
+none = NoneType()
+
+
 class CodeType(Type):
     def __init__(self, language: builtins.str) -> None:
         self.language = language